Referring to FIG. 1A, a conventional light guide lens 1, which is used with a light emitting diode (LED) 10, includes a main body 11 having a light incident surface 12 that faces the LED 10 and that is concave away from the LED 10, and a cambered light exiting surface 13 that is opposite to the light incident surface 12. Light emitted from the LED 10 is first refracted at the light incident surface 12, and then refracted again at the cambered light exiting surface 13. Hence, alight emitting angle of the light emitting module is increased.
Since the light emitting module tends to be thinned for commercial demand, the conventional light guide lens 1 is desired to have a reduced thickness to shorten an optical path required for light mixing of a plurality of the light emitting modules. However, reduction in the thickness of the conventional light guide lens 1 will unavoidably harmful to breadth of the light emitting angle of the light emitting module. Hence, there is plenty of room for improvement in a light guide lens of a light emitting module for having a desired lens thickness without sacrificing the breadth of the light emitting angle of the light emitting module.